Source of global warming is ultimately the sun. Without the sun, our small, insignificant
planet Earth would be adrift in cold, empty space. Its only heat would come from whatever heat remained from its creation or from whatever is generated within it.

It has been hypothesized that greenhouse gases trap solar insolation the Earth receives from the sun. Carbon dioxide is one of the heaviest gases in the atmosphere. As a gas, concentrations of carbon dioxide (CO2) hold close to ground level. Thus, this blanketing effect then causes blackbody radiation to be entrapped near the earth's surface. Blackbody radiation is emitted from the earth when its surface is away from the Sun.

The best evidence of global warming is not in the rise of global temperatures but in the loss of perennial snow and glaciers.

The earth's albedo is a ratio of solar energy reflected back into space and blackbody radiation emitted at night to the total incident solar energy received during the day. As mountain and oceanic glaciers melt less sunlight is reflected back into space. The photographical evidence suggests that the earth's glaciers are melting at an increasing rate. And as these glaciers continue to retreat, more solar insolation is trapped near the earth's surface.

Either an increase in carbon dioxide levels or a decrease in reflected solar radiation will raise the aledo.